●Activity: An activity represents a single screen with a user interface. ●Service: A service is a component that runs in the background to perform long-running operations or to perform work for remote processes. ●Content providers: A content provider manages a shared set of app data.Through the content provider, other apps can query or even modify the data (if the content provider allows it). ●Broadcast receivers: A broadcast receiver is a component that responds to system-wide broadcast announcements. ●Shared Preferences: Store private primitive data in key-value pairs.